Crown type tooth



Dec. 31, 1946. ER ON 2,413,333 C-ROWN TYPE TOOTH 7 Filed NOV. 25, 1942 1%; azz 5- Patented Dec. 31, 1946 UNITED STATES PATENT OFFICE 2,413,333 CROWN TYPE TOOTH Simon Myerson, Brookline, Mass.

Application November 25, 1942, Serial No. 466,845

13 Claims.

This invention pertains to artificial teeth and relates more especially to crown type teeth, the present application being a continuation-in-part of my copending application Serial No. 261,717, filed May 14, 1939. Said application discloses an improved tooth construction designed to permit grinding the tooth in adjusting the bite without thereby impairing the effectiveness of the attaching means, as well as to provide an arrangement of the tooth surfaces and pin such as to insure a reliably firm anchorage of the tooth to the material of the denture in which the tooth is mounted, and at the same time to provide a more desirable contour of the lingual surface of the denture teeth.

The present invention concerns further improvements with the objects, among others, of providing a tooth having an unusually long anchoring pin having improved retentive characteristics, a pin which if necessary may be shortened, as by grinding, should conditions require, without unduly impairing its retentive qualities; to provide a tooth of the crown type so shaped at its gingival end as to insure adequate anchorage of the attaching pin in the denture material; to provide a tooth having its attaching pin so located that it will reliably oppose tipping of the tooth in response to biting forces; to provide a tooth which when mounted in the denture will have in effect a substantially full crown labial surface; and to provide a. tooth which when mounted in the denture will have a more natural feel to the tongue, and a more natural appearance when viewed from the front than usual prior teeth when similarly mounted.

These and other objects and advantages herein more fully pointed out, are obtained by the construction disclosed in the following more detailed description and illustrated in the accompanying drawing, wherein Fig. 1 is a vertical section, to large scale, illustrating a preferred embodiment of the tooth, and indicating a portion of a plate in which the tooth is set;

Fig. 1 is a section similar to Fig. 1 but to smaller scale, showing the tooth alone;

Fig. 2 is a rear elevation of the tooth of Fig. 1;

Fig. 3 is a rear elevation of .a tooth of a modified construction;

Fig. 4 is a section on the line i4 of Fig. 3;

Fig. 5 is a section similar to Fig. 4, showing a further modification, the attaching pin being bent slightly downward;

Fig. 6 is a section similar to Fig. 4, but illustrating a further modification;

Fig. 7 is a view generally similar to Fig. 1, but illustrating a preferred arrangement of tooth and p Fig. 8 is a large scale rear elevation of a preferred form of attaching pin; and

Fig. 9 is a transverse section of the attaching pin of Fig. 8.

Referring to the drawing, in particular to Figs.

1, 1 and 2, the numeral I designates the improved tooth which in all particulars, other than those hereinafter specifically pointed out, may be of any desired type, material and construction. As illustrated, this tooth has the incisal edge 2, the mesial and distal edges 3 and 4 respectively, the lingual surface 5, and the labial surface 6. The gingival or basal surface I of this tooth is actually merely a substantially U-shaped narrow rim forming the margin of a gingival cavity 8. However, for convenience in relatively locating parts, it may be assumed that the gingival face is that geometrical surface which is defined by this rim. This cavity opens at the lingual surface of the tooth and as illustrated has a substantially fiat upwardly and forwardly sloping floor 9 having the forward edge IB. Forwardly of the edge Ill, the gingival cavity 8 is preferably deeper than the portion 8 which lies directly above the floor 9, thus providing a deep forward pocket ll (Fig. 1 While this arrangement is preferable, it is contemplated that for some purposes it will be satisfactory to extend the floor 9 forwardly to the extreme front wall of the cavity. Thefloor 9 intersects the lingual wall 5 of the tooth along the line [2 (Fig. 2). Preferably this line of intersection is located at a point approximating the horizontal mid-plane XY of the tooth, that is to say, the line I2 is preferably nearly midway between the incisal edge and the horizontal edge O--P (Fig. 2) of the extreme upper end' of the tooth.

An attaching pin I3 is embedded in the substance of the tooth, this pin having a head or collar M which is preferably located below the horizontal mid-plane XY of the tooth. The pin emerges from the substance of the tooth at a point in the floor 9. This point of emergence of the pin from the floor is preferably between the lingual surface and the mid-point of the tooth measured along the plane W-Z of the floor 9. The pin is unusually long, as herein illustrated, so that a substantial part projects beyond the gingival face I, emerging from the gingival face between the lingual edge and mid-point of the gingival face. The exposed portion of the pin is provided with means to facilitate its firm anchorage in the plate material. Thus, as illustrated in Figs. 1, 2 and 8, a substantial length of the exposed portion of the pin is provided with a coarse screw thread or helical rib it. Instead of a helical rib, a series of parallel annular ribs, lugs, or other distinct projecting elements may be provided along the length of the pin. By providing such anchorage means throughout a substantial length of the pin, it is possible, if necessary, to cut away materially from the outer or rear end of the pin and still leave sufficient of this anchorage means to insure firm retention in the plate material. As compared with this arrangement, a pin of the usual type having a single head or enlargement at its rear end, if shortened, loses its retaining means. i

In the arrangement illustrated in Fig. 7, the attaching pin I3 is so located asto extend obliquely upward and rearward at such an angle that in the average set-up it would pass below the crest of thegum ridge, the upper side of the peripheral' surface of the rear end portion of the pin lying close to and beneath the gum ridge and being in fact almost tangent to the lingual portion of the crest of the gum ridge, the axis of the pin following the same general direction as the lower portion of the palatal part of the plate. A s bstantial length of the pin may thus be emb dd d in the palatal portion of the plate withoutnecessitating a substantialthickening of the plate immediately below the crest of the gum ridge such as is commonly necessary when using teeth having pins which project horizontally. Statedin another way, the axis of the pin is so inclined rearwardly and upwardly and the pin is of such length that if that portion of the lingual surface of the tooth which is intersected by the bottom wall of the cavity were extended upwardly (without change of direction) it would intersect the rear end of the pin. It is manifest that this arrangement of the pin affords the maximum resistance to tipping of the tooth by biting pressure.

In Fig. 1, the improved tooth is shown as mounted in a plate to form a denture. The roof rpalatal portion of the plate is indicated at I5, and ,thatportion which receives the gum ridge is indicated at I6} As illustrated, the portion l6 is thin and the gingival end 'I of the tooth may thus be disposed very close to the surface of the gum ridge. As shown in Fig. 1, the rear end of the pin l3 is embedded in this portion 15 of the plate. The part [6 has an integral, forwardly and dQWnwardly directed extension H which fills the gingival cavity 8 of the tooth. This part H is of substantial depth at the forward part it of the cavity, thus aifording an anchorage between the plate material and the tooth efifective to resist the forward thrust of the biting force. The, plate, material also fills the slot 8 (Fig. 1) thus forming the extension Il (Fig. 1). The rear end of this extension l'l of the plate materialis exposed at the lingual surface of the tooth. It will be noted that that portion of the attaching pin I3 which is exposed is unusually long as compared with the ordinary tooth-attaching pins and that the entire length of this exposed portion may be embedded in plate mate rial even though the gingival end of the tooth is positioned very close to the gum ridge as at Fig. '7. As illustrated in Fig. 7, it may be advisable to bend the pin slightly so as to avoid interference with the gum ridge. For this purpose the pin is indentedby compression at 25, without loss of crosssection at the point of compression. This enables the pin to be bent without danger of fracture of the tooth. By reference to Figs. 1 and '7 it may be observed that the location and direction of the axis of the pin l3 are such as to afford a great mechanical advantage to resist displacement forces and at the same time to permit considerable grinding away of the gingival end of the tooth. The forward part of the tooth is supported very rigidly by a body of plate material extending doWn into the gingival cavity and the rearwardly located pin has a very long portion embedded in the plate material.

In the arrangement of Fig. 7 the gingival end of the tooth l is even closer to the gum ridge than in Fig. 1. This is a very desirable relationship of tooth and gum ridge in many cases. The end portion of the pin is very close to the gum. Should it be necessary for aesthetic or functional reasons to raise the tooth slightly; to grind the gingival end; or to tilt. it inwardly, the end of the pin it might normally interfere with the desired positioning of the tooth. This interference can be readily overcome, either by shortening, or by grinding away one side of the pin, or by slightly bending the pin downwardly. The'pin would still have adequate retention in the plate material. Such adjustment is frequently necessary, and in the construction here disclosed the tooth may be shortened by grinding its gingival surface and thus adapting it to the gum ridge without danger of damage to the strength of the tooth or retention in the denture. The lingual opening El permits downward bending of the pin and becomes filled with denture material in processing. This denture material is readily made flush with the edges of the slot and does not interfere with the natural lingual contour of the tooth.

Figs. 3, 4 and 5 illustrate modifications. The tooth 5 is furnished with a vertical slot 23 which extends downwardly from the gingival surface I to the lingual surface 5 The slot 23 has a floor or wall 24 at which the pin [3 emerges from the substance of the tooth, the rear portion of the pin being partly within the slot 23. A substantial length of the pin is thus free so that it maybe bentupwardly or downwardly from its normal position.

To facilitate bending of the pin as above described, the pin may, if desired, be of the transverse section shown in Figs. 8 and 9. As there illustrated, the pin l3 has a shank portion which is flattened or of more or less elliptical contour, the major axis of the ellipse being arranged to extend transversely of the tooth when the pin is inserted. s

As illustrated in Fig. 5, the upper or basel portion of the tooth has been ground away, but preparatory to so doing the pin may be bent as indicated at HE so as to avoid injury thereto in the grinding operation, and after the tooth has been cut away to the desired extent it is still possible, by properly disposing the exposed part of the pin,

to obtain a firm and secure anchorage of the pin to the material of the plate.

In Fig. 5 the pin is of a type somewhat different from that of Figs. 3 and 4. Here the pin i3 has an inner head which is embedded in the substance of the tooth. The rear end portion of the pin is located in the cavity or slot 23 and the thus exposed shank portion of the pin is screw threaded for the reception of a nut M which may be screwed along the threaded shank so as to occupy any desired position.

In Fig. 6 a further arrangement is illustrated wherein the pin I3 has a threaded inner or forward end engaging an internally threaded collar K embedded in the tooth substance. Forwardly of the collar the tooth has a bore B designed to receive the end portion of the pin with clearance, thus permitting the exposed portion of the pin to be effectively shortened (by screwing the pin downwardly into the tooth) preparatory to grinding the gingival end of the tooth.

Throughout the specification and in the claims the terms up or down are used in relation to an upper tooth as pictured in the drawing. The meaning of the terms would be reversed in referring to a lower tooth in its natural position.

While certain desirable embodiments of the invention have been illustrated by way of example, it is to be understood that the invention is not necessarily limited to these precise embodiments, but is to be regarded as broadly inclusive of any and all modifications and substitutions falling within the scope of the appended claims.

I claim:

1. An artificial tooth comprising a labial face, a lingual face and a gingival face, the tooth having therein a cavity which is open both at the gingival and lingual faces of the tooth, the cavity having a wall which intersects the lingual face, and a substantially straight pin whose forward end is permanently anchored in the substance of the tooth and which emerges from the tooth substance at a point in said wall of the cavity and which is of such length as to extend beyond the gingival face.

2. An artificial tooth having therein a gingival cavity and an attaching pin for anchoring it to a support, the pin being fixedly embedded at its forward end in the substance of the tooth and inclining upwardly and extending rearwardly through said cavity and beyond the gingival surface of the tooth, the cavity having a wall which intersects the lingual surface of the tooth at a point below the horizontal mid-plane of the tooth, and the pin emerging from said wall into the cavity.

3. An artificial tooth having a labial face, a lingual face and a gingival face, the tooth having a cavity in said gingival face, one wall of the cavity intersecting the lingual face, and a pin having one end embedded in the substance of the tooth, the pin emerging from said wall of the gingival cavity at a point between the lingual face and the mid-point of the tooth as measured along said wall.

4. An artitficial tooth having a labial face, a lingual face and a gingival face, the latter being of substantially U-shape and constituting the margin of a cavity, one wall of which intersects the lingual face, and a pin embedded in said tooth and emerging from the substance of the tooth at a point in said wall of the cavity, the pin extending beyond the gingival face and the aXis of the pin intersecting the gingival face at a point Within the posterior half of the latter.

5. An artificial tooth having a labial face, a lingual face and a gingival face, the latter having a cavity therein, the cavity having a front wall, spaced side walls and a wall which intersects the lingual face, the forward portion of the cavity being deeper than its rear portion, and a pin emerging from the substance of the tooth at a point in that wall of the cavity which intersects the lingual face, the point of emergence of the pin being in the rearward portion of the cavity and the pin being of such length as to extend beyond the ginival face.

6. An artificial tooth having a labial'face, a lingual face and a gingival face, the latter havin therein a cavity whose forward portion i deeper than its rear portion, the rear portion of the cavity having a substantially flat wall which intersects the lingual face, and a pin emerging from said fiat wall within the rearward portion of the cavity, the pin being of such length as to extend beyond the gingival face.

7. An artificial tooth comprising a labial face, a lingual face and a gingival face, the latter being of the substantially U-shape and constituting the margin of a cavity one wall of which intersects the lingual face, and an anchoring pin having one end embedded in the substance of the tooth, the pin emerging from said latter wall of the cavity and being of such length as to extend upward through the cavity and to project beyond the gingival face of the tooth, the pin being so inclined that when set in a denture its rear portion is embedded in and follows the same general direction as the lower portion of the palatal part of the plate with the peripheral surface of said rear end portion below and close to the crest of the gum ridge.

8. An artificial tooth having a labial face, a lingual face, and a gingival face of substantially U-shape constituting the margin of a cavity, said cavity having a rearwardly and downwardly sloping wall which intersects the lingual face, and an anchoring pin having one end embedded in the tooth substance and emerging from said wall into the cavity, the pin being of such length as to extend beyond the gingival face and being substantially perpendicular to said wall at its point of emergence from the latter.

9. An artificial tooth havin a labial face, a lingual face and a gingival face, the latter face having therein a cavity provided with a wall which intersects the lingual face, and an anchoring pin having one end embedded in the substance of the tooth, the pin emerging from said wall of the cavity and being of such length as to project beyond the gingival face of the tooth, the

, pin being so located and inclined that were that portion of the lingual face which is intersected by the side wall of the cavity extended upwardly without change of direction it would intersect the rear end portion of the pin.

10. A crown type tooth comprising a labial face, a lingual face and a gingival face, the tooth having therein a cavity one wall of which intersects the lingual face, and an anchoring pin embedded in the tooth and emerging from the substance of the tooth at a point in said wall for- 5 wardly of the lingual face, the pin being so located and of such length as to project beyond the gingival face and intersecting the gingival face at a point in the posterior half of the latter, the pin extending obliquely upwardly at such an angle that when the tooth is set in a denture the upper side of the peripheral surface of the rear portion of the pin will lie close to and beneath the lingual surface of the crest of the gum ridge.

11. An artificial tooth having a labial face, a lingual face and a gingival face, the tooth having therein a cavity which opens at the gingival face of the tooth and which has a front wall and spaced side walls, the cavity also having a wall which intersects thelingual face of the tooth, and a pin emerging from the substance of the tooth at a point in said latter wall which is within the rearward portion of the cavity, the pin being so shaped at a point close to its emergence from the substance of the tooth that it is more easily bent upwardly or downwardly than laterally.

12. A crown type tooth having a cavity in its gingival end, said cavity having a wall which intersects the lingual face of the tooth andan attaching pin or generally circular cross-section having one end embedded in the tooth substance, the pin emerging from the tooth substance at a point in said wall and having a short portion of its length, located adjacent to its point of emergence from said wall, which is constructed and arranged to facilitate bending it in a front-torear direction more easily than in a lateral direction, the exposed portion of the pin being of such a length as normally to reach beyond the gingival surface.

8 13. A crown type tooth having a cavity in its gingival face, said cavity having a Wall which intersects the lingual face of the tooth, and an attaching pin having one end embedded in the tooth substance, the pin emerging from the tooth substance at a point in said wall and extending rearwardly beyond the gingival face, a part, at least, of the exposed portion of the pin being substantially elliptical in transverse section with the major axis of the ellipse extending crosswise of the tooth whereby the pin is more easily bent up-and-down than transversely, the exposed portion of the pin having anchoring means extending longitudinally thereof.

SIMON MYERSON. 

